/*
  Parsing.cpp - HTTP request parsing.

  Copyright (c) 2015 Ivan Grokhotkov. All rights reserved.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  Modified 8 May 2015 by Hristo Gochkov (proper post and file upload handling)
*/

#include <Arduino.h>
#include "WiFiServer.h"
#include "WiFiClient.h"
#include "WebServer.h"

//#define DEBUG_ESP_HTTP_SERVER
#ifdef DEBUG_ESP_PORT
#define DEBUG_OUTPUT DEBUG_ESP_PORT
#else
#define DEBUG_OUTPUT Serial
#endif

static char* readBytesWithTimeout(WiFiClient& client, size_t maxLength,
                                  size_t& dataLength, int timeout_ms) {
    char* buf  = nullptr;
    dataLength = 0;
    while (dataLength < maxLength) {
        int tries = timeout_ms;
        size_t newLength;
        while (!(newLength = client.available()) && tries--) delay(1);
        if (!newLength) {
            break;
        }
        if (!buf) {
            buf = (char*)malloc(newLength + 1);
            if (!buf) {
                return nullptr;
            }
        } else {
            char* newBuf = (char*)realloc(buf, dataLength + newLength + 1);
            if (!newBuf) {
                free(buf);
                return nullptr;
            }
            buf = newBuf;
        }
        client.readBytes(buf + dataLength, newLength);
        dataLength += newLength;
        buf[dataLength] = '\0';
    }
    return buf;
}

bool WebServer::_parseRequest(WiFiClient& client) {
    // Read the first line of HTTP request
    String req = client.readStringUntil('\r');
    client.readStringUntil('\n');
    // reset header value
    for (int i = 0; i < _headerKeysCount; ++i) {
        _currentHeaders[i].value = String();
    }

    // First line of HTTP request looks like "GET /path HTTP/1.1"
    // Retrieve the "/path" part by finding the spaces
    int addr_start = req.indexOf(' ');
    int addr_end   = req.indexOf(' ', addr_start + 1);
    if (addr_start == -1 || addr_end == -1) {
#ifdef DEBUG_ESP_HTTP_SERVER
        DEBUG_OUTPUT.print("Invalid request: ");
        DEBUG_OUTPUT.println(req);
#endif
        return false;
    }

    String methodStr  = req.substring(0, addr_start);
    String url        = req.substring(addr_start + 1, addr_end);
    String versionEnd = req.substring(addr_end + 8);
    _currentVersion   = atoi(versionEnd.c_str());
    String searchStr  = "";
    int hasSearch     = url.indexOf('?');
    if (hasSearch != -1) {
        searchStr = urlDecode(url.substring(hasSearch + 1));
        url       = url.substring(0, hasSearch);
    }
    _currentUri = url;
    _chunked    = false;

    HTTPMethod method = HTTP_GET;
    if (methodStr == "POST") {
        method = HTTP_POST;
    } else if (methodStr == "DELETE") {
        method = HTTP_DELETE;
    } else if (methodStr == "OPTIONS") {
        method = HTTP_OPTIONS;
    } else if (methodStr == "PUT") {
        method = HTTP_PUT;
    } else if (methodStr == "PATCH") {
        method = HTTP_PATCH;
    }
    _currentMethod = method;

#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("method: ");
    DEBUG_OUTPUT.print(methodStr);
    DEBUG_OUTPUT.print(" url: ");
    DEBUG_OUTPUT.print(url);
    DEBUG_OUTPUT.print(" search: ");
    DEBUG_OUTPUT.println(searchStr);
#endif

    // attach handler
    RequestHandler* handler;
    for (handler = _firstHandler; handler; handler = handler->next()) {
        if (handler->canHandle(_currentMethod, _currentUri)) break;
    }
    _currentHandler = handler;

    String formData;
    // below is needed only when POST type request
    if (method == HTTP_POST || method == HTTP_PUT || method == HTTP_PATCH ||
        method == HTTP_DELETE) {
        String boundaryStr;
        String headerName;
        String headerValue;
        bool isForm            = false;
        bool isEncoded         = false;
        uint32_t contentLength = 0;
        // parse headers
        while (1) {
            req = client.readStringUntil('\r');
            client.readStringUntil('\n');
            if (req == "") break;  // no moar headers
            int headerDiv = req.indexOf(':');
            if (headerDiv == -1) {
                break;
            }
            headerName  = req.substring(0, headerDiv);
            headerValue = req.substring(headerDiv + 1);
            headerValue.trim();
            _collectHeader(headerName.c_str(), headerValue.c_str());

#ifdef DEBUG_ESP_HTTP_SERVER
            DEBUG_OUTPUT.print("headerName: ");
            DEBUG_OUTPUT.println(headerName);
            DEBUG_OUTPUT.print("headerValue: ");
            DEBUG_OUTPUT.println(headerValue);
#endif

            if (headerName.equalsIgnoreCase("Content-Type")) {
                if (headerValue.startsWith("text/plain")) {
                    isForm = false;
                } else if (headerValue.startsWith(
                               "application/x-www-form-urlencoded")) {
                    isForm    = false;
                    isEncoded = true;
                } else if (headerValue.startsWith("multipart/")) {
                    boundaryStr =
                        headerValue.substring(headerValue.indexOf('=') + 1);
                    isForm = true;
                }
            } else if (headerName.equalsIgnoreCase("Content-Length")) {
                contentLength = headerValue.toInt();
            } else if (headerName.equalsIgnoreCase("Host")) {
                _hostHeader = headerValue;
            }
        }

        if (!isForm) {
            size_t plainLength;
            char* plainBuf = readBytesWithTimeout(
                client, contentLength, plainLength, HTTP_MAX_POST_WAIT);
            if (plainLength < contentLength) {
                free(plainBuf);
                return false;
            }
            if (contentLength > 0) {
                if (searchStr != "") searchStr += '&';
                if (isEncoded) {
                    // url encoded form
                    String decoded    = urlDecode(plainBuf);
                    size_t decodedLen = decoded.length();
                    memcpy(plainBuf, decoded.c_str(), decodedLen);
                    plainBuf[decodedLen] = 0;
                    searchStr += plainBuf;
                }
                _parseArguments(searchStr);
                if (!isEncoded) {
                    // plain post json or other data
                    RequestArgument& arg = _currentArgs[_currentArgCount++];
                    arg.key              = "plain";
                    arg.value            = String(plainBuf);
                }

#ifdef DEBUG_ESP_HTTP_SERVER
                DEBUG_OUTPUT.print("Plain: ");
                DEBUG_OUTPUT.println(plainBuf);
#endif
                free(plainBuf);
            }
        }

        if (isForm) {
            _parseArguments(searchStr);
            if (!_parseForm(client, boundaryStr, contentLength)) {
                return false;
            }
        }
    } else {
        String headerName;
        String headerValue;
        // parse headers
        while (1) {
            req = client.readStringUntil('\r');
            client.readStringUntil('\n');
            if (req == "") break;  // no moar headers
            int headerDiv = req.indexOf(':');
            if (headerDiv == -1) {
                break;
            }
            headerName  = req.substring(0, headerDiv);
            headerValue = req.substring(headerDiv + 2);
            _collectHeader(headerName.c_str(), headerValue.c_str());

#ifdef DEBUG_ESP_HTTP_SERVER
            DEBUG_OUTPUT.print("headerName: ");
            DEBUG_OUTPUT.println(headerName);
            DEBUG_OUTPUT.print("headerValue: ");
            DEBUG_OUTPUT.println(headerValue);
#endif

            if (headerName.equalsIgnoreCase("Host")) {
                _hostHeader = headerValue;
            }
        }
        _parseArguments(searchStr);
    }
    client.flush();

#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("Request: ");
    DEBUG_OUTPUT.println(url);
    DEBUG_OUTPUT.print(" Arguments: ");
    DEBUG_OUTPUT.println(searchStr);
#endif

    return true;
}

bool WebServer::_collectHeader(const char* headerName,
                               const char* headerValue) {
    for (int i = 0; i < _headerKeysCount; i++) {
        if (_currentHeaders[i].key.equalsIgnoreCase(headerName)) {
            _currentHeaders[i].value = headerValue;
            return true;
        }
    }
    return false;
}

void WebServer::_parseArguments(String data) {
#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("args: ");
    DEBUG_OUTPUT.println(data);
#endif
    if (_currentArgs) delete[] _currentArgs;
    _currentArgs = 0;
    if (data.length() == 0) {
        _currentArgCount = 0;
        _currentArgs     = new RequestArgument[1];
        return;
    }
    _currentArgCount = 1;

    for (int i = 0; i < (int)data.length();) {
        i = data.indexOf('&', i);
        if (i == -1) break;
        ++i;
        ++_currentArgCount;
    }
#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("args count: ");
    DEBUG_OUTPUT.println(_currentArgCount);
#endif

    _currentArgs = new RequestArgument[_currentArgCount + 1];
    int pos      = 0;
    int iarg;
    for (iarg = 0; iarg < _currentArgCount;) {
        int equal_sign_index = data.indexOf('=', pos);
        int next_arg_index   = data.indexOf('&', pos);
#ifdef DEBUG_ESP_HTTP_SERVER
        DEBUG_OUTPUT.print("pos ");
        DEBUG_OUTPUT.print(pos);
        DEBUG_OUTPUT.print("=@ ");
        DEBUG_OUTPUT.print(equal_sign_index);
        DEBUG_OUTPUT.print(" &@ ");
        DEBUG_OUTPUT.println(next_arg_index);
#endif
        if ((equal_sign_index == -1) ||
            ((equal_sign_index > next_arg_index) && (next_arg_index != -1))) {
#ifdef DEBUG_ESP_HTTP_SERVER
            DEBUG_OUTPUT.print("arg missing value: ");
            DEBUG_OUTPUT.println(iarg);
#endif
            if (next_arg_index == -1) break;
            pos = next_arg_index + 1;
            continue;
        }
        RequestArgument& arg = _currentArgs[iarg];
        arg.key              = data.substring(pos, equal_sign_index);
        arg.value = data.substring(equal_sign_index + 1, next_arg_index);
#ifdef DEBUG_ESP_HTTP_SERVER
        DEBUG_OUTPUT.print("arg ");
        DEBUG_OUTPUT.print(iarg);
        DEBUG_OUTPUT.print(" key: ");
        DEBUG_OUTPUT.print(arg.key);
        DEBUG_OUTPUT.print(" value: ");
        DEBUG_OUTPUT.println(arg.value);
#endif
        ++iarg;
        if (next_arg_index == -1) break;
        pos = next_arg_index + 1;
    }
    _currentArgCount = iarg;
#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("args count: ");
    DEBUG_OUTPUT.println(_currentArgCount);
#endif
}

void WebServer::_uploadWriteByte(uint8_t b) {
    if (_currentUpload.currentSize == HTTP_UPLOAD_BUFLEN) {
        if (_currentHandler && _currentHandler->canUpload(_currentUri))
            _currentHandler->upload(*this, _currentUri, _currentUpload);
        _currentUpload.totalSize += _currentUpload.currentSize;
        _currentUpload.currentSize = 0;
    }
    _currentUpload.buf[_currentUpload.currentSize++] = b;
}

uint8_t WebServer::_uploadReadByte(WiFiClient& client) {
    int res = client.read();
    if (res == -1) {
        while (!client.available() && client.connected()) yield();
        res = client.read();
    }
    return (uint8_t)res;
}

bool WebServer::_parseForm(WiFiClient& client, String boundary, uint32_t len) {
    (void)len;
#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("Parse Form: Boundary: ");
    DEBUG_OUTPUT.print(boundary);
    DEBUG_OUTPUT.print(" Length: ");
    DEBUG_OUTPUT.println(len);
#endif
    String line;
    int retry = 0;
    do {
        line = client.readStringUntil('\r');
        ++retry;
    } while (line.length() == 0 && retry < 3);

    client.readStringUntil('\n');
    // start reading the form
    if (line == ("--" + boundary)) {
        RequestArgument* postArgs = new RequestArgument[32];
        int postArgsLen           = 0;
        while (1) {
            String argName;
            String argValue;
            String argType;
            String argFilename;
            bool argIsFile = false;

            line = client.readStringUntil('\r');
            client.readStringUntil('\n');
            if (line.length() > 19 &&
                line.substring(0, 19).equalsIgnoreCase("Content-Disposition")) {
                int nameStart = line.indexOf('=');
                if (nameStart != -1) {
                    argName   = line.substring(nameStart + 2);
                    nameStart = argName.indexOf('=');
                    if (nameStart == -1) {
                        argName = argName.substring(0, argName.length() - 1);
                    } else {
                        argFilename = argName.substring(nameStart + 2,
                                                        argName.length() - 1);
                        argName   = argName.substring(0, argName.indexOf('"'));
                        argIsFile = true;
#ifdef DEBUG_ESP_HTTP_SERVER
                        DEBUG_OUTPUT.print("PostArg FileName: ");
                        DEBUG_OUTPUT.println(argFilename);
#endif
                        // use GET to set the filename if uploading using blob
                        if (argFilename == "blob" && hasArg("filename"))
                            argFilename = arg("filename");
                    }
#ifdef DEBUG_ESP_HTTP_SERVER
                    DEBUG_OUTPUT.print("PostArg Name: ");
                    DEBUG_OUTPUT.println(argName);
#endif
                    argType = "text/plain";
                    line    = client.readStringUntil('\r');
                    client.readStringUntil('\n');
                    if (line.length() > 12 &&
                        line.substring(0, 12).equalsIgnoreCase(
                            "Content-Type")) {
                        argType = line.substring(line.indexOf(':') + 2);
                        // skip next line
                        client.readStringUntil('\r');
                        client.readStringUntil('\n');
                    }
#ifdef DEBUG_ESP_HTTP_SERVER
                    DEBUG_OUTPUT.print("PostArg Type: ");
                    DEBUG_OUTPUT.println(argType);
#endif
                    if (!argIsFile) {
                        while (1) {
                            line = client.readStringUntil('\r');
                            client.readStringUntil('\n');
                            if (line.startsWith("--" + boundary)) break;
                            if (argValue.length() > 0) argValue += "\n";
                            argValue += line;
                        }
#ifdef DEBUG_ESP_HTTP_SERVER
                        DEBUG_OUTPUT.print("PostArg Value: ");
                        DEBUG_OUTPUT.println(argValue);
                        DEBUG_OUTPUT.println();
#endif

                        RequestArgument& arg = postArgs[postArgsLen++];
                        arg.key              = argName;
                        arg.value            = argValue;

                        if (line == ("--" + boundary + "--")) {
#ifdef DEBUG_ESP_HTTP_SERVER
                            DEBUG_OUTPUT.println("Done Parsing POST");
#endif
                            break;
                        }
                    } else {
                        _currentUpload.status      = UPLOAD_FILE_START;
                        _currentUpload.name        = argName;
                        _currentUpload.filename    = argFilename;
                        _currentUpload.type        = argType;
                        _currentUpload.totalSize   = 0;
                        _currentUpload.currentSize = 0;
#ifdef DEBUG_ESP_HTTP_SERVER
                        DEBUG_OUTPUT.print("Start File: ");
                        DEBUG_OUTPUT.print(_currentUpload.filename);
                        DEBUG_OUTPUT.print(" Type: ");
                        DEBUG_OUTPUT.println(_currentUpload.type);
#endif
                        if (_currentHandler &&
                            _currentHandler->canUpload(_currentUri))
                            _currentHandler->upload(*this, _currentUri,
                                                    _currentUpload);
                        _currentUpload.status = UPLOAD_FILE_WRITE;
                        uint8_t argByte       = _uploadReadByte(client);
                    readfile:
                        while (argByte != 0x0D) {
                            if (!client.connected())
                                return _parseFormUploadAborted();
                            _uploadWriteByte(argByte);
                            argByte = _uploadReadByte(client);
                        }

                        argByte = _uploadReadByte(client);
                        if (!client.connected())
                            return _parseFormUploadAborted();
                        if (argByte == 0x0A) {
                            argByte = _uploadReadByte(client);
                            if (!client.connected())
                                return _parseFormUploadAborted();
                            if ((char)argByte != '-') {
                                // continue reading the file
                                _uploadWriteByte(0x0D);
                                _uploadWriteByte(0x0A);
                                goto readfile;
                            } else {
                                argByte = _uploadReadByte(client);
                                if (!client.connected())
                                    return _parseFormUploadAborted();
                                if ((char)argByte != '-') {
                                    // continue reading the file
                                    _uploadWriteByte(0x0D);
                                    _uploadWriteByte(0x0A);
                                    _uploadWriteByte((uint8_t)('-'));
                                    goto readfile;
                                }
                            }

                            uint8_t endBuf[boundary.length()];
                            client.readBytes(endBuf, boundary.length());

                            if (strstr((const char*)endBuf, boundary.c_str()) !=
                                NULL) {
                                if (_currentHandler &&
                                    _currentHandler->canUpload(_currentUri))
                                    _currentHandler->upload(*this, _currentUri,
                                                            _currentUpload);
                                _currentUpload.totalSize +=
                                    _currentUpload.currentSize;
                                _currentUpload.status = UPLOAD_FILE_END;
                                if (_currentHandler &&
                                    _currentHandler->canUpload(_currentUri))
                                    _currentHandler->upload(*this, _currentUri,
                                                            _currentUpload);
#ifdef DEBUG_ESP_HTTP_SERVER
                                DEBUG_OUTPUT.print("End File: ");
                                DEBUG_OUTPUT.print(_currentUpload.filename);
                                DEBUG_OUTPUT.print(" Type: ");
                                DEBUG_OUTPUT.print(_currentUpload.type);
                                DEBUG_OUTPUT.print(" Size: ");
                                DEBUG_OUTPUT.println(_currentUpload.totalSize);
#endif
                                line = client.readStringUntil(0x0D);
                                client.readStringUntil(0x0A);
                                if (line == "--") {
#ifdef DEBUG_ESP_HTTP_SERVER
                                    DEBUG_OUTPUT.println("Done Parsing POST");
#endif
                                    break;
                                }
                                continue;
                            } else {
                                _uploadWriteByte(0x0D);
                                _uploadWriteByte(0x0A);
                                _uploadWriteByte((uint8_t)('-'));
                                _uploadWriteByte((uint8_t)('-'));
                                uint32_t i = 0;
                                while (i < boundary.length()) {
                                    _uploadWriteByte(endBuf[i++]);
                                }
                                argByte = _uploadReadByte(client);
                                goto readfile;
                            }
                        } else {
                            _uploadWriteByte(0x0D);
                            goto readfile;
                        }
                        break;
                    }
                }
            }
        }

        int iarg;
        int totalArgs = ((32 - postArgsLen) < _currentArgCount)
                            ? (32 - postArgsLen)
                            : _currentArgCount;
        for (iarg = 0; iarg < totalArgs; iarg++) {
            RequestArgument& arg = postArgs[postArgsLen++];
            arg.key              = _currentArgs[iarg].key;
            arg.value            = _currentArgs[iarg].value;
        }
        if (_currentArgs) delete[] _currentArgs;
        _currentArgs = new RequestArgument[postArgsLen];
        for (iarg = 0; iarg < postArgsLen; iarg++) {
            RequestArgument& arg = _currentArgs[iarg];
            arg.key              = postArgs[iarg].key;
            arg.value            = postArgs[iarg].value;
        }
        _currentArgCount = iarg;
        if (postArgs) delete[] postArgs;
        return true;
    }
#ifdef DEBUG_ESP_HTTP_SERVER
    DEBUG_OUTPUT.print("Error: line: ");
    DEBUG_OUTPUT.println(line);
#endif
    return false;
}

String WebServer::urlDecode(const String& text) {
    String decoded   = "";
    char temp[]      = "0x00";
    unsigned int len = text.length();
    unsigned int i   = 0;
    while (i < len) {
        char decodedChar;
        char encodedChar = text.charAt(i++);
        if ((encodedChar == '%') && (i + 1 < len)) {
            temp[2] = text.charAt(i++);
            temp[3] = text.charAt(i++);

            decodedChar = strtol(temp, NULL, 16);
        } else {
            if (encodedChar == '+') {
                decodedChar = ' ';
            } else {
                decodedChar = encodedChar;  // normal ascii char
            }
        }
        decoded += decodedChar;
    }
    return decoded;
}

bool WebServer::_parseFormUploadAborted() {
    _currentUpload.status = UPLOAD_FILE_ABORTED;
    if (_currentHandler && _currentHandler->canUpload(_currentUri))
        _currentHandler->upload(*this, _currentUri, _currentUpload);
    return false;
}
